WASHINGTON (June 30, 2012)--Rarely are presidents presented with the kind of defining moment that President Barack Obama experienced when the Supreme Court upheld his health care law this week.

The ruling will transcend his presidency, change America's social safety net and shape how he is likely to be remembered but there’s a catch.

If Mr. Obama doesn't win a second term, he risks losing both the law and the core of his legacy because Republican Mitt Romney vows to try to gut the law and replace it with something else.

All the rest of what Mr. Obama accomplishes will fall under the dimmer view of history assigned to one-term presidents.

For now, the campaign retains its focus and remains a contest between two men with vastly different visions about how to fix the economy.